Checked over numerous reviews.Compaired w/other brands at REI. Most bang for the buck, Bought it for a 3 day 185 mile trip on the C&O canal. Worked great,plenty of room for clothes and gear. I had no problems with any of the zippers. Combined with the Topeak QR Beam rack it's an unbeatable combination...

Weaknesses: Not enough separate pouches, I would have liked some inside main compartment for wallet & phone since the side pouches hold gloves, minitool, arm warmers etc etc with no room left. The main compartment zippers are very fiddly.

Bottom Line:

Liked the bag, bought it mainly for the slide-on rails to go with the Topeak QR beam rack. The main zippers are hidden under the zip flap and are not that easy to operate. 3 chilis for value - a bit expensive.

Strengths: Compact, but expandable. Quick Release (when used with topeak rack). Light, works well as locker back for commuters, fits perfectly in gym locker even when panniers expanded. Great volume. Panniers can hold a standard 2" 3 ring binder, main compartment like a shoe box.

Weaknesses: Inside has two pen holders, a flat pouch, and a gussetted elastic pouch. All are worthless, for once you open the bag, things fly all over. Zippered/Buttoned/velco pouches would be more useful. Will probably sew a few pieces of velcro in myself.

Bottom Line:

I got a topeak rack and bag from big-wheel.com

It's not this model, but it's close.

See this image for the exact bag I'm reviewing:http://www.wiggle.co.uk/images/topeak%20qt%20trunk%20bag%20mx%20ind.jpg

It was only $45 at big-wheel.com

It's an awesome bag, big enough to fit my business casual attire for the day, my lunch, bike accessories, and even a three ring binder or two when fully expanded.

When compacted (so it's just the center part), it's about the size of a shoe box, a big enough one that I can still fit by business casual attire in it, but no lunch or binders :)

I use it with their QT rack, which means no tying down the bag, it slides into a slot and has a locking mechanism that is easy to release.

It's the best purchase I've made for my bike to work so far.

The other day, I even carted home a 12 pack of pepsi, and two two-liters of soda in the thing (top of bag didn't close) leaving my hands completely free.

Being behind you, it has minimal drag, and it's not very heavy. As an added bonus, the bag fits PERFECT in a gym locker, even when fully expanded.

Weaknesses: Would be nice if there was a tailight loop similar to their wedge bags.

Bottom Line:

I love this bag when paired with their QT rack. Once you've used this feature it's hard to imagine using a conventionl attachment system. Just came back from a hudered mile weekend trip in PA where all it did was pour rain. This bag kept everything in the main compartment dry. Stuff in the side pockets got a little damp from water entering through the side zippers which don't have a storm flap. When loaded it would sometimes slide to the side a little, although that is really an issue with the post. Put a taillight loop on it and cover those zippers and I would give it a five. As is I'll give it a four for value and a four overall.